Use of hydrosulphites or sulfoxylates in the removal of dyes from textile fibers



Patented A 3,1926.

UNITED A PATENT-OFFICE.

oHAELEs s. noLLANnEE, or PHILADELPHIA, PENNSYLVANIA, ASSIGNOR ro RUM & HAAS COMPANY, A CORPORATION OF DELAWARE.

pen or EtYnnosuEPnI'rEs on suproxrna'rns IN run REMOVAL or nrE's EnoII TEXT LE EInEns.

Ho Drawing.

an alkali, either of which would cause it to' dissolve rapidly. However, acids have a very injurious action on vegetable fibers,

Whereas, alkalis damage animal fibers. Accordingly, this 'material has not been considered as being readily available for stripping dyes from mixed fabrics.

T have now found that basic zinc sulfo xylate formaldehyde can be used as a stripping agent in the presence of a salt such as sodium chloride, sodium sulphate,'sodium acetate, potassium chloride, potassium sulphate, ammonium chloride or ammonium sulphate as well as many others. These salts all of which include use base a substance whose hydroxide is strongly alkaline), while they may show some acid or alkaline reaction to litmus, are substantially neutral in efiect as regards the injury to either animal or vegetable'fibers. I therefore classify them broadly under the term substantially neutral salts of substances whose hydroxides are strongly alkaline]? It may be noted that so all of these salts are readily soluble in water. When such a neutral salt' is used the basic zinc sulfoxylate formaldehyde doesnot go quickly acid or an alkali is used, but nevertheless does accomplish the desired result. Basic zinc sulfoxylate formaldehyde is ordinarily classed as an insoluble substance. However,

in hot water it will form a slight solution (of approm'mately 1%. strength) and this is 40 suflicientto cause the foregoing reaction to 7 take place. -Despite the fact that this material is thus slightly soluble, it may properly be termed a substantiallyinsolublesulfoxylate formaldehyde. An explanation of this would be that in water solution, especially into solution as is the case when an.

Application am 'June a, 1925. Serial No. 36,022;

,when heated, an equilibrium is established according to the formula:

formald 'The water soluble ammonium sulfoxylate ehyde inthis case accomplishes the the equilibrium andmore ammonium sulfoxylate; formaldehyde is' formed until the desired result is accomplished.

' The following are given as examples of my process, but it is to be understood that; they are given 0111 by way of illustration,- and I do not inten to limit myself as to the time, temperature, percentages, proportions or sequence of operations:

First emampZe..-100 parts of dyed goods composed of wool and cotton were heated with enough water to completely" immerse them. 10% of a mixture of equal parts of basic zinc sulfoxylate formaldehyde and of ammonium chloride were added and stirred in. The goods were then heated at a temperature of 180 had i be F. to 212 F, until the color en discharged. They were then rinsed throughly with water and dried in the usual manner.

Second armada-J00 parts of a mixture of silk and cotton fibers may be discharged by immersing them in water, bringing to boil and adding 5% of basic zinc sulfoxy late formaldehyde and 5 to 10% of ordinary table salt. The boiling should continue until all the dye has been discharged then throughly rinsed and dried in the usual 7 It may be found necessary to prepare the goods for the the adhering soap solution employe WhatIclaim iszly the boiling point during the stripping 1. Process of stripping dyes from dyed operation. materials which consists in immersing such 3. A composition of matter adapted for materials in a mixture of a substantially inuse in stripping dyes from textile fabrics 8 soluble sulfoxylate formaldehyde and a and the like, comprising a mixture of sub- 1 readily soluble substantially neutral salt of stantially insoluble sulfoxylate formaldea substance whose hydroxide is strongly alhyde and a readily soluble, substantially kaline.. neutral salt of a substance whose hydroxide 2. A process as defined in claim 1, in is strongly alkaline. 1 which the solution isheatedto approximate- CHAS. S. HOLLANDER. 

